The low spatial charge-storage density of porous carbons greatly limits volumetric performance in electrochemical capacitors.An increase of charge-storage density requires structural refinements to balance the trade-o...The low spatial charge-storage density of porous carbons greatly limits volumetric performance in electrochemical capacitors.An increase of charge-storage density requires structural refinements to balance the trade-offs between the porosity and density of materials,but the limited mechanical properties of carbons usually fail to withstand effective densifying processes and obtain an ideal pore structure.Herein,we design the stiffened graphene of superior bending rigidity,enabling the fine adjustments of pore structure to maximize the volumetric capacitance for the graphene-based electrodes.The inplane crumples on graphene sheets are found to contribute largely to the bending rigidity,which is useful to control the structural evolution and maintain sufficient ion-accessible surface area during the assembling process.This makes the capacitance of stiffening activated graphene keep 98%when the electrode density increases by 769%to reach 1.13 g cm^(-3) after mechanical pressure,an excellent volumetric energy density of 98.7 Wh L^(-1) in an ionic-liquid electrolyte is achieved.Our results demonstrate the role of intrinsic material properties on the performance of carbon-based electrodes for capacitive energy storage.展开更多
Biomass is rich,renewable,sustainable,and green resources,thereby excellent raw material for the fabrication of carbon materials.The diversity in structure and morphology of biomass are relevant in obtaining carbon ma...Biomass is rich,renewable,sustainable,and green resources,thereby excellent raw material for the fabrication of carbon materials.The diversity in structure and morphology of biomass are relevant in obtaining carbon materials with dif-ferent structures and performances.The inherent ordered porous structure of biomass also benefits the activation process to yield porous carbons with ultra-high specific surface area and pore volume.Besides,obtained biomass-derived carbons(BDCs)are hard carbon with porous morphology,stable structure,supe-rior hardness/strength,and good cycling performances when used in electro-chemical capacitors(ECs).The inherent N,S,P,and O elements in biomass yield naturally self-doped N,S,P,and O BDCs with unique intrinsic structures.In this paper,the synthesis approaches and applications of BDCs in ECs are reviewed.It shows that BDCs electrochemical performances are highly determined by their pore structures,specific surface areas,heteroatoms doping,graphitization degree,defects,and morphologies.The electrochemical performances of BDCs can further be improved by compositing with other materials,such as graphene,carbon nanofibers/nanotubes,transition metal oxides or hydroxides,and con-ducting polymers.The future challenges and outlooks of BDCs are also provided.展开更多
基金financial support from the National Natural Science Foundation of China(22078164,and 22079164)the Major Special Projects of the Plan“Science and Technology Innovation 2025”in Ningbo(2019B10045)。
文摘The low spatial charge-storage density of porous carbons greatly limits volumetric performance in electrochemical capacitors.An increase of charge-storage density requires structural refinements to balance the trade-offs between the porosity and density of materials,but the limited mechanical properties of carbons usually fail to withstand effective densifying processes and obtain an ideal pore structure.Herein,we design the stiffened graphene of superior bending rigidity,enabling the fine adjustments of pore structure to maximize the volumetric capacitance for the graphene-based electrodes.The inplane crumples on graphene sheets are found to contribute largely to the bending rigidity,which is useful to control the structural evolution and maintain sufficient ion-accessible surface area during the assembling process.This makes the capacitance of stiffening activated graphene keep 98%when the electrode density increases by 769%to reach 1.13 g cm^(-3) after mechanical pressure,an excellent volumetric energy density of 98.7 Wh L^(-1) in an ionic-liquid electrolyte is achieved.Our results demonstrate the role of intrinsic material properties on the performance of carbon-based electrodes for capacitive energy storage.
基金National Natural Science Founda-tion of China,Grant/Award Numbers:52062012,51525206,520105010,21603048Key Science&Technology Project of Hainan Province,Grant/Award Number:ZDYF2020028。
文摘Biomass is rich,renewable,sustainable,and green resources,thereby excellent raw material for the fabrication of carbon materials.The diversity in structure and morphology of biomass are relevant in obtaining carbon materials with dif-ferent structures and performances.The inherent ordered porous structure of biomass also benefits the activation process to yield porous carbons with ultra-high specific surface area and pore volume.Besides,obtained biomass-derived carbons(BDCs)are hard carbon with porous morphology,stable structure,supe-rior hardness/strength,and good cycling performances when used in electro-chemical capacitors(ECs).The inherent N,S,P,and O elements in biomass yield naturally self-doped N,S,P,and O BDCs with unique intrinsic structures.In this paper,the synthesis approaches and applications of BDCs in ECs are reviewed.It shows that BDCs electrochemical performances are highly determined by their pore structures,specific surface areas,heteroatoms doping,graphitization degree,defects,and morphologies.The electrochemical performances of BDCs can further be improved by compositing with other materials,such as graphene,carbon nanofibers/nanotubes,transition metal oxides or hydroxides,and con-ducting polymers.The future challenges and outlooks of BDCs are also provided.
